Display of stereoscopic images has long been known. Two visual images of the same scene are presented to a viewer, but one being at a slightly different viewing angle to the other. Means such as a physical barrier, or polarized or colored glasses cause the different images to be viewed only by corresponding individual eyes. The brain merges these images seen by different eyes into a single three dimensional image having the illusion of depth.
Stereoscopic displays have been provided on computer screens by displaying the two images sequentially on a single display in different colors, the images being separated for presentation to each eye of the user by means of colored filters in glasses worn by the user. Unfortunately since each of the images must be presented in a separate scanning process, the result has been the perception of undesirable flicker.
In addition, the images being required to be presented in separate colors requires the computer displays to be able to present different colors, which is costly since color displays must be used, and substantially eliminates the possibility of presentation of the stereoscopic image to the user using a monochrome display. A large number of portable computers utilize a monochrome display, often for the reason of cost, and therefore this technique cannot be used with inexpensive monochrome displays such as are contained in portable computers.